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The Durable Press Finishing of Silk Fabrics by Using 1,2,3,4-Butanetetracarboxylic Acid

Zhuohong Yang1, 2 and Jinlian Hu2

1College of Science, South China Agriculture University, Guangzhou, P. R. China 2Institute of Textiles and Clothing, The Hong Kong Polytechnic University,

Hung Hom, Kowloon, Hong Kong

ABSTRACT

In this paper, the nonformaldehyde agent 1,2,3,4-butanetetracarboxylic acid was used for durable press finishing of silk fabric. To optimize the finishing, the effects of the amount of sodium hypophosphite, 1,2,3,4-butanetetracarboxylic acid and citric acid, curing temperature and curing time were examined. It was found that the wet wrinkle recovery angle had an obvious improvement from 179° to 273°, and that the finishing had a very small effect to the breaking strength. Keywords: Silk, Durable Press Finishing, Butanetetracarboxylic Acid

1. Introduction To the present, 1,2,3,4-butanetetracarboxylic acid (BTCA) was found to be the most effective nonformaldehyde durable press finishing reagent [1-4]. It has been considered that the polycarboxylic acid reacted with cotton to form crosslinks through ester linkages between the cellulose and the agent (Schramm et al., 1998; Xu et al., 2001). Recently, much research work has been done on the Durable Press (DP) finishing of cotton (Blanchard and Graves, 2002; Zhou et al., 2002; Yang et al., 2001; Yang, 2001). While silk as very exalted fabrics originated from China and has similar structure compared with cotton because both of which have many hydroxy groups, little attention has been given. Since the DP finishing is also very important to silk, the BTCA was chosen for the DP finishing of silk fabrics in this paper. Moreover, the relation among each finishing variable, the amount of sodium hypophosphite (SHP), BTCA and Citric acid (CA), curing temperature, curing time and the finished fabric’s properties, including breaking strength and wet wrinkle recovery angle were also investigated.

2. Experimental 2.1 Materials Undyed 100% silk was purchased from WuXi Silk Factory. 1,2,3,4-butanecarboxylic acid was

prepared according to the literature (Toshihiro et al.). Citric acid, SHP, triethanolamine (TEA) and Boric acid were purchased from Beijing Chemical Company and were analytical grade. Softener (SG-6) and permeate agent (JFC) were purchased from Jiangsu Hai’an Chemistry Company.

2.2 Silk Durable Press Treatment The silk was immersed in the aqueous treating solution containing BTCA, CA, SHP and other reagents of different amounts. The fabric was then passed through squeeze rolls and immersed in the treating solution, and was then passed through squeeze rolls again to give a specified wet pick-up of ca.100%. The fabric was pre-dried at 80°C, and cured in a second oven for 2 minutes at 170°C ~175°C.

2.3 Testing Methods Mechanical properties were measured on an Instron tester (model 3410) at a 50 mm gauge length and with a crosshead speed of 100 mm/min. The width of the sample was 15 mm. As the silk has a good dry wrinkle recovery angle, only the wet wrinkle recovery angle was measured in this paper. Standard methods were used to measure the wet wrinkle recovery angle (AATCC 66-1996).

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3. Results and Discussion

3.1 The Effect of BTCA Amount to the DP Finishing

Table 1. The relation of BTCA amount with wet

WRA and breaking strength retention of silk fabric

BTCA

(%) Wet

WRA Breaking Strength

Retention (%) 3 244.7° 103.6 4 248.0° 97.0 6 255.7° 85.3 7 255.7° 101.5 8 236.0° 107.0

Untreated sample

179.0° 100

Note. The durable press finishing also contained 3.0% SHP, 2.0% triethanolamine, 1.0% SG-6, 0.5% JFC, 0.5% Boric acid, followed by predrying at 80°C for 5 minutes, curing in a second oven at 170°C for 2 minutes. At first, the effect of BTCA amount was investigated and the results are summarized in Table 1. We found that the BTCA amount had an obvious influence on the properties of finished fabrics: With the increase of BTCA to 7%, the wet WRA increased up to 255.7°; while the use of 8% only led to the wet WRA of 236°. We consider that the elasticity of fabric would decrease when the fabric had an exceeded crosslinking with BTCA, which led to the decrease of wet WRA. With the breaking strength considered, 7% of BTCA seemed to have the best result of WRA for the experiments reported here.

3.2 The Effect of the Amount of SHP to the

DP Finishing

Table 2. The effect of the amount of SHP

SHP (%)

TEA (%)

Wet WRA

Breaking Strength Retention (%)

2 2 227.3° 87.0 3 2 255.7° 85.3 4 2 270.4° 85.8 5 2 264.6° 87.4 3 3 254.7° 93.2

Note. The durable press finishing also contained 7.0% BTCA, 1.0% SG-6, 0.5% JFC, 0.5% Boric acid, followed by predrying at 80°C for 5 minutes, curing in a second oven at 170°C for 2 minutes.

In the DP finishing of cotton with BTCA, SHP is a very important factor as a catalyst. In addition, the amount of SHP is even more critical to the finishing. Therefore, we also investigated the effect of the SHP amount and the results are shown in Table 2. From the results, we found that the wet WRA was markedly influenced by the amount of SHP. When the fabric was treated with 4% SHP and 2% TEA, the wet WRA greater than 270° was obtained with 85.8% breaking strength reserved.

3.3 The Choice of Curing Temperature and

Time It is reasonable to try to decrease the curing time by using a relatively high temperature. However, higher temperature leads to the breaking-down of the fabric polymer and the decrease of strength, which can be seen from the results in Table 3. When the finished fabric was cured at 170°C for 2 minutes, the best finishing result was obtained with 273° of wet WRA and 87.5% of breaking strength retention.

Table 3. The DP finishing with different

curing temperature and time

T. (°C)

Time (min)

Wet WRA

Breaking Strength Retention (%)

170 1.5 253.3° 88.3 170 2.0 273.0° 87.5 170 3.0 255.7° 85.3 175 1.5 264.6° 105.6 175 2.0 254.0° 95.5 175 3.0 258.7° 71.6

Note. The durable press finishing also contained 7.0% BTCA, 4.0% SHP, 2.0% triethanolamine, 1.0% SG-6, 0.5% JFC, 0.5% Boric acid, followed by predrying at 80°C for 5 minutes.

3.4 The Mixed Finishing of BTCA with CA

Table 4. The wet WRA and breaking strength

retention of the fabric treated by BTCA mixed with CA.

BTCA

(%) CA (%)

Wet WRA

Breaking Strength Retention (%)

4 3 229.7° 110.7 4.5 2.5 238.4° 105.7 5 2 242.7° 96.4

5.5 1.5 222.6° 103.1 6 1 249.0° 87.6

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Note. The durable press finishing also contained 4.0% SHP, 2.0% triethanolamine, 1.0% SG-6, 0.5% JFC, 0.5% Boric acid, followed by predrying at 80°C for 5 minutes, curing in a second oven at 170°C for 2 minutes.

Although BTCA has a good finishing result, the high cost of BTCA is an obstacle to mills’ decisions to use BTCA. As mixed polycarboxylic acids has been an interesting research area for decreasing the expense of using BTCA by reducing the required amount of BTCA in DP finishing, the finishing of BTCA mixed with CA was also investigated in this paper. The results are shown in Table 4. It is evident that the wet WRA decreased when smaller amount of BTCA mixed with CA was used in the DP finishing, although the breaking strength retention did not vary too much. As CA was considered to have lower activity than BTCA (Xu and Shyr, 2000), in the same condition, CA could not have a complete crosslink with silk fabrics. To obtain better finishing results with CA, other methods should be considered.

3.5 FTIR Analysis FTIR analysis is a very important analysis method in the DP finishing (Yang, 2001). In this paper, the FTIR was also used to study the crosslink of BTCA with silk fabrics. Compared with the FTIR of silk structure, the finished fabric appeared an obvious absorption at 1700~1750 cm-1, which was usually considered the feature of ester and could be proved that BTCA has successfully crosslinked with the silk fabric. 4. Conclusion This paper reported the durable press finishing of silk fabrics with BTCA. The effect of the finishing variables, SHP, BTCA and CA amounts, curing temperature and curing time were investigated. The results showed that BTCA is a very effective reagent to the DP finishing of silk fabrics. The optimized finishing variables were given and up to 273° of wet WRA was obtained with 87.5% breaking strength retention reserved. In addition, the effects of different processing conditions on DP of silk fabrics have been studied.

REFERENCE

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[8] Yang, C.Q. 2001, ‘FTIR Spectroscopy Study of Ester Crosslinking of Cotton Cellulose Catalyzed by Sodium Hypophosphite’, Textile Research Journal, vol. 71, no. 3, pp. 201-206.

[9] Yang, C.Q., Qian, L. & Lickfield, G.C. 2001, ‘Mechanical strength of durable press finished cotton fabric part IV: Abrasion resistance’, Textile Research Journal, vol. 71, no. 6, pp. 543-548.

[10] Yang, C.Q., Wang, X.L. & Kang, I.S. 1997, ‘Ester crosslinking of cotton fabric by polymeric carboxylic acids and citric acid’, Textile Research Journal, vol. 67, no. 5, pp. 334-342.

[11] Zhou, L.M., Yeung, K.W. & Yuen, C.W.M. 2002, ‘Treating cotton fabric with cellulase and BTCA in one bath’, AATAA-Review, vol. 2, no. 1, pp. 29-33.